In one aspect, this invention relates to candle-making. In another aspect, this invention relates to an apparatus for making candles.
Decorative candles have developed into a very large business in the United States. These candles vary over a wide range in size. For example, heights can range from about xc2xd inch to about 12 inches, and diameters can range from about xc2xc inch to 8 inches. The candles are generally made of wax derived from petroleum and are often colored and scented.
Petroleum wax shrinks a great deal when it solidifies. The shrinkage affects the shape of larger candles more than smaller ones. The shrinkage has made it difficult to make acceptably appearing candles of over about an inch in diameter in an automated, single pass process, and manual techniques have to be used. While candles having a diameter of three inches and upward have a sufficiently high retail price to recover their high cost of production, it has been extremely difficult to profitably produce candles having a diameter in the range of 1-3 inches. This is unfortunate, as candles having a diameter of about two inches are very popular with consumers.
An automated process for candle production would be very desirable, especially an automated process which is well suited for the production of candles having a diameter in the range of one to three inches.
It is an object of this invention to provide a method for making candles in which the effect of shrinkage on candle appearance is minimized.
It is a further object of this invention to provide an apparatus for making candles in which the production of large diameter candles is largely automated.
In commonly encountered temperature ranges, candle wax exists in states of matter ranging from runny liquid to thick liquid to soft solid to hard solid. Under relatively mild pressure conditions, the wax can be caused to flow when in the soft solid state. The inventive concept is to apply pressure during this stage of hardening during the candle making process to cause the wax to completely fill the mold cavity, thereby largely avoiding shape imperfections in the finished candle blank.
As applied to a process for making a candle blank, the invention can be carried out by first injecting a volume of hot liquid candle wax into a generally cylindrical chamber having a length and a diameter. The hot liquid candle wax is then cooled, to at least a semi-solid state. The wax shrinks as it cools, The length of the generally cylindrical chamber is reduced as the wax cools, so that the volume of the chamber remains substantially that of the volume of the shrinking wax. By operating in this manner, there is no room for a void to form.
An apparatus which embodies the inventive concept comprises a block, a piston, a gate, a means to inject the wax, and a means to move the piston so that it follows the shrinkage of the wax as it solidifies. The block defines a generally cylindrical mold chamber for the candle blank. The mold chamber has a generally vertically positioned longitudinal axis, an upper end, and a lower end. The piston is positioned in the chamber to slide from the upper end to the lower end of the chamber. The gate is positioned at a lower end of the chamber. The gate is pivotally mounted to the block so as to move from a first position which seals the lower end of the chamber to a second position in which the gate does not impede the ejection of the candle blank from the chamber. The apparatus further comprises a means for injecting hot liquid wax into the chamber between the gate and the piston and a means for biasing the piston toward the gate to reduce chamber volume as the hot liquid wax cools. This prevents the production of a candle blank having a substantial void.